I'd like to see what hwloc reports on AMD machines with a HTX card
(hypertransport expansion card). The most widely known case would likely
be a 3-5-years old AMD cluster with Pathscale Infinipath network cards.
But I think there are also some accelerators such as clearspeed, and the
numaconnect single-image interconnect.

HTX slots do not involve PCI, but AMD may have implemented some glue to
make them appear in lspci anyway. So it's not clear if hwloc will see
them or not.

If anybody has access to such a machine, could you please run lstopo
(>=1.3) there and tell us if the HTX device appear? if not, we'll need
to see if there are some /dev files to look at. If yes, does it appear
close to a single socket ? If so, is this the right socket ? (feel free
to tell what model of machine this is, I will check in the motherboard
manual to make sure this is the right socket).